Armor Class vs To Hit chance

I don't quite understand how my Armor Class will affect my enemy's To Hit chance against me, and vice versa.

For example, if my Base To Hit = 125%, and my enemy's Armor Class is 15, what will be my To Hit chance to hit my enemy, 110?
Is that how it works or there is a different pattern?

Any thoughts are appreciated.

 

Well, I must admit that I've never bothered to figure out the exact numbers. Suffice it to say that a high AC increases the chance for your opponent to miss (and vice versa) so it's something you'll want. DR is superior to AC when it comes to limiting damage taken though.

I also believe that your AC temporarily increases by a number equal to you remaining action points if you end your turn with any left. Or maybe that's Fallout?